Flush type resistor element for temperature measurements



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FLUSH TYPE RESISTOR ELEMENT FOR v I TEMPERATURE MEASUREKENTS 2f nimm 'W mented M a, i949 FLUSH TYPE RESISTOB ELEMENT FOB TEMPERATURE MEASUBEMENTS Karl M.' Lederer, Newark, N. J., asignar to Weston Electrical Instrument Corporation, Newark,

N. J., a corporation of New Jersey Application March 18, 1946, Serial No. 655,064

(Cl. 201-63l 9 Claims. l

This invention relates to resistor elements and particularly to resistor elements for use in electrical apparatus for the measurement of temperature.

.The usual type of resistor element or resistance bulb is housed within an elongated cylindrical shell of small diameter which may or may not be provided with a mounting head. Such devices are employed on aircraft for the measurement of the free air temperature, i. e. the temperature of the air outside of and adjacent the aircraft. The resistor element and/or its supporting structure extended into free air beyond a surface of an airfoil or the fuselage, and such a construction obviously resulted in appreciable wind resistance.

An object is to provide resistor elements for use in temperature measurements, the resistor elements being located within casings having one wall adapted for mounting flush with the outer surface of an airfol or with the inner Wall of a gas or air passage. An object is to provide a resistor element for use in measuring the temperature of air or a fluid, the temperature-variant resistance of the resistor element being a spiral winding, preferably a biiiler winding, cemented to the inner surface of a thin metal sheet which is to be mounted flush with the surface of an airfoil or other wall contacted by the air or fluid. Further objects are to provide resistor elements for location substantially flushwith an airfoil surface, and mountings for such resistor elements which are movable to prevent accumulations of ice on the resistance elements.

These and other objects and advantages of the invention will be apparent from the following specification when taken with the accompanying drawing in which:

Fig. 1 is an enlarged central section through a resistor element embodying the invention;

Fig. 2 is a rear or inside elevation of the same with parts broken vaway to show the resistance winding and terminal connections;

Fig. 3 is a perspective view of the terminal block on a greatly enlarged scale;

Fig. 4 is a central section through the terminal block, showing the parts of one terminal in position for assembly, and another terminal asl sembled and in place on the block;

of stainless steel, which has a shallow rear flange 2 snugly fitted over and secured to the forward end of a small casing l of insulating material by cement l. The casing 3 has an intermediate flange 5 `which projects laterally beyond the periphery of the metal plate I and has apertures I for receiving the screws by which the casing may be mounted on a boundary wall, for example on the interior surface of an airfoil, to locate the metal plate I in an opening of the boundary wall and flush with the surface thereof which is contacted by the air or other medium whose temperature is to be measured. A cable connector 1 is secured to the rear of the casing 3, and a gasket 8 between the connector flange and the casing provides a hermetic seal for the interior of the casing.

The resistance winding or windings are cemented to the interior surface of the plate I, and may comprise a single spirally wound coil or the plurality of coils which are conventional in bridge type measuring circuits and in compensated reslstor bulb systems. For simplicity of illustration. only a single resistance winding 9 is shown in Figs. 1 and 2. 'Ihe winding 9 is a spiral coil, and preferably a biler coil, of ne enamel-coated copper wire of a diameter of two mils or less which is wound between closely spaced plates in conventionaimanner and coated with an insulating varnish to form a self-supporting disk which can be removed from the winding form and transferred to the inner surface of the plate I. The coil 9 is secured to the plate I by insulating varnish or cement I0, and the outer ends II of the bilar coil are connected to each other after adjustment of their length to provide a predetermined resistance at a selected temperature of calibration. The coil 9 is of excess length as initially wound and the insulation is removed from the outer ends II after the coil is cemented to the plate I. The bared ends II are then twisted together to shorten the effective length of the winding progressively until the measured resistance of the coil is reduced to the preselected value for the temperature at which this calibration is made. Any excess wire length is cut oil, and the joined ends II are cemented to the plate I.

The inner ends I2V of the winding 9 are of course 'secured to. terminal connections before thisV adjustment of the effective length and rel end extending through and staked over the mounting block I3. The mounting blocks I3 could be manufactured in three types to receive two, three or four terminal connectors in accordance with the particular design of the resistance windings and the measuring circuits but it is more economical to use a single "standard mounting block I3 with four sockets I5 for receiving the required number of terminal connectors for the several types of resistance windings. The block I3 has bores'IS which extend transversely of the sockets I5 to receive an end I2 of a resistance winding, and grooves ill which lead into the several sockets I5 to receive the projectlng ends of soldering lugs I8 of the terminal connectors.

As best shown in Fig. 4, each connector comprises a stud or bolt I9 with an inner head 20 and an outer threaded end for receiving a nut 2i for clamping the soldering lug i8, a spring washer 22 and a washer or bushing 23 upon the end l2 of a winding which is threaded through the bore i6 of the insulating mounting [lo and the transverse opening I6 through the stud i9. After the terminal connector is clamped upon the winding end I2, the connector is'secured in place within its socket i5 by Wax or varnish. Flexible leads 24 are soldered between the lugs it and the terminals 25 of the cable connector l.

The described flush type ci resistor element is well ladapted for measurement of the free air temperature at the surface oi an airioil so long as the outer surface oi the plate i is not covered by ice. The resistor .element is preferably mounted for limited movement with respect to the airfoil to crack ice deposits from the plate i. As shown in Figs. 5 and 7, the resistor assembly is mounted on airfoil 2b, and with the plate i normally flush with the surface of the airfoil, by means of an annular cap 2li having an outer flange which is secured to studs 28 fixed to the airfoil and an inner flange which extends over the inner face of the housing il of the resistor assembly. A hollow ring 2@ of rubber or other resilient material is arranged between the airioil 2t and the radial ilange 5 of the housing, and a similar hollow ring Si@ is arranged between the rear face of the flange 5' and the inner flange of the cap 2l. The flexible ring il@ has an inlet Si for connection to a source of pulsating pressure air, not shown, which vibrates the resistor housing 3 continuously or intermittently to re move deposits of ice. A plurality of Studs 32 are threaded into the housing 3 and extend through the mounting cap 2li to guide the housing for axial movement.

Another form of de-icing mounting, as shown in Figs. 6 and 8, comprises a hollow flexible ring 3l]- between the flange 5 of the resistor housing 3 and a plate 33 which is mounted on studs 3d secured to the airfoil 2d. Coiled compression Lil) springs 35 are arranged on the studs 3ft between the airfoil 26 and the housing flange 5 to press the flange 5 rearwardly and position the plate l flush Iwith the airfoil surface when pressure air is not admitted to the exible ring 35i'. The admission of pressure air to the ring Si), either cyclically or manually at intervals, forces the resistor assembly outwardly to crack ice deposits from the surface of the plate i to which the resistor winding is secured.

It is to be understood that Ithe invention is not limited to the embodiments herein shown and described as various modifications which may occur to those familiar with the design and con- 4 struction of resistor elements for temperature measuring systems fall within the spirit and scope of the invention as set forth in the following claims.

I claim:

1. A resistor element for incorporation in a temperature measuring system, said resistor element comprising a metal plate having one surface for engagement by the material whose temperature is to be measured, a closely-wound single layer spiral resistance winding of fine enamelinsulated wire and means adhesively securing said winding to the other surface of said plate.

2. A resistor element as recited in claim 1, in combination with an insulating member secured to said other surface of the plate and substantially centrally of said winding, terminal connectors carried by said insulating member and including means for. securing the ends of said winding thereto.

3. A resistor element as recited in claim l, wherein said winding is a bifilar winding of preselected resistance value at a given temperature, said winding having its outer ends electrically connected to each other at a point which provides said preselected resistance value, in combination with terminal connectors supported on said plate within said spiral resistance winding, the inner ends of` said Winding being mechanically and electrically connected to said terminal connectors.

4. A resistor element comprising an insulating casing, a metal plate extending across and closing one end of said casing, a resistance winding cemented to .the inner surface of said plate, terminal connections for said winding extending through the other end of said casing, and means supporting said terminai connections and sealing said other end oi the casing.

5. A resistor element as recited in claim i wherein said terminal connections include an insulating block secured to the inner surface of said plate within said winding, and terminal connectors supported on said insulating block; said winding being a bilar winding with cuter ends electrically connected to each other and inner ends connected to said terminal connectors.

6. A resistor element comprising a casing having a metal plate closing one end thereof, a resistance winding cemented to the inner surface of said plate, a boundary wall having an opening therethrough, and means mounting said casing on said boundary wall with said plate in the opening thereof; said mounting means including means for vibrating said casing with respect to said boundary wall.

7. A resistor element comprising a casing hav ing a metal plate closing one end thereof, a resistance winding cemented to the inner surface of said plate, a boundary Wall having an opening therethrough, and means mounting said 'casing on said boundary wall with said plate in the opening thereof; said mounting means including a hollow expansible element for displacing said plate with respect to said boundary wall upon the introduction of a pressure medium into said expansible element.

8. A resistor element comprising a casing with an intermediate flange and having a metal plate closing one end thereof, a resistance winding cemented to the inner surface of said plate, a boundary wall having an opening therethrough, and means mounting said casing on said boundary wall with said plate in the opening thereof; said mounting means including a cap with an outer ilange secured to said boundary wall and 8 6 an inner danze in lxini siinexnent with said REFERENCES CITED intermediate flange, s hollow expansible element between said casing iiange and the inner cap minst fliswggeferences are of record m the iiange for displacing said plate with respect to said boundary wail upon the introduction of a i UNITED STATES PATENTS pressure medium into said expansible element. Number Name Date 9. A resistor element as in claim 8, Potstada Jan. wherein resilient means is positioned between 2318102 Ruge May 4 1943 said boundary wail and said intermediate iiange. 213561858 Laurence Aug. 29 1944 KARL M- LEDERER- 2,373,255 MeGoldrick Apr. 1o, 1945 

